Hydraulic pump-motor combination



Sept. 16, 1969 H. G. ALLEN 3,467,015

HYDRAULIC PUMP-MOTOR COMBINATION Filed March 28, 1968 5 Sheets-Sheet 1 I /2 O, 3 l

I z z 1 i z I j I N 1 ll8 I20 I 2 T/ r-)- so 82 62 E Q 6 64 r so 7 72 5 4H2 58 I II E 108 0 FIG. I.

I06 Q5 I 92 88 9 WITNESSES? INVENTOR 9i6 HOfvey I! 1 94 ATTORNEY United States Patent US. Cl. 103-87 12 Claims ABSTRACT OF THE DISCLOSURE A pump-motor combination is assembled to a vertical cylindrical tank suspended from a plant deck and the like. The motor is mounted on a flange at the upper end of the tank at floor level and the hydraulic pump component is hung vertically from the motor support within the tank. The tank carries a pool of liquid metal which submerges the hydraulic elements of the pump. The suction and discharge pipe connections are at the lower end of the tank. Inert gas fills the space between the liquid level and the deck shielding. The pump component is removable from the tank as a unit.

BACKGROUND OF THE INVENTION This invention relates, generally, to hydraulic pumps and, more particularly, to large capacity centrifugal pumps for handling liquid metal at high temperatures.

The building of large pumps for liquid metal systems is a relatively new business. In pump structures produced up to this time, a major consideration was the best arrangement of the suction and discharge flow to and from the pump and also to have suitable pump disconnect joints. A satisfactory arrangement of these joints was made difficult because of the thermal expansion and contraction of the connecting column and shafting between the pump and the motor. In prior structures, an attempted solution of this problem has been to provide only one joint at the discharge connection, thereby requiring that the pump take suction directly from the tank sump. However, this arrangement creates other difiiculties, such as:

(1) Fluid turbulence within the sump, making it more diflicult to maintain a stable gas to liquid interface.

(2) Carrying flow through the sump introduces hydraulic losses with detrimental efiect on the net positive suction head (NPSH) (3) This arrangement places the sump at pump suction pressure, the lowest pressure point within the pumping system, which creates a diflicult liquid level control problem.

An object of this invention is to provide a centrifugal pump structure which overcomes the foregoing difliculties.

Other objects of the invention will be explained fully hereinafter or will be apparent to those skilled in the art.

SUMMARY OF THE INVENTION In accordance with one embodiment of the invention, a hydraulic pump-motor combination is assembled to a vertical cylindrical tank suspended from a supporting structure, such as a plant deck and the like. The motor support is mounted at the upper end of the tank at floor level; and the pump component extends downwardly from the motor support within the tank. The hydraulic component structure comprises two basic parts, a centrifugal pump unit suspended from the motor support, and a suction and discharge header which forms the bottom of the tank. A pool of liquid metal in the tank submerges the hydraulic elements of the pump. Suction and discharge pipe connections are at the lower end of the tank. Inert gas 'ice fills the space between the liquid metal and the deck shielding. Slip joints connecting the pump unit and the suction and discharge header provide for removal of the complete pump unit for maintenance. The joints are free to move axially permitting axial movement, caused by temperature transients, between the pump and the tank.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the nature and objects of the invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a view, in vertical section, of a centrifugal pump-motor combination embodying princpal features of the invention; and

FIGS. 2 and 3 are views, in vertical section, of two different hydraulic components suitable for use in the pump-motor combination.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawings, and particularly to FIG. 1, the hydraulic pump-motor combination shown therein comprises a supporting structure 10, a generally cylindrical tank 12, a motor support 14, a centrifugal pump 16, a suction and discharge header 18 which forms the bottom of the tank 12, and a pump shaft 20* which extends vertically through the motor support 14. Only a portion of a base 22 for the motor which drives the pump 16 through the shaft 20 is shown in the present drawing. The driving motor may be of any suitable type having a vertical shaft which is connected to the shaft 20 by means of a coupling 24 only a portion of which is shown.

In the present drawing, the supporting structure 10 is illustrated as a concrete deck. The supporting structure may be the floor of a building or it may be a structural steel framework capable of supporting the pump-motor combination. As shown, the tank 12 has an outwardly extending flange 26 and a shoulder 28 which rests on the concrete of the deck shielding 10, thereby suspending the tank from the supporting structure.

A plug comprising a metal container 30, which is of a cake pan shape having a tubular sleeve 32 extending vertically through the central portion of the container, is mounted at the top of the supporting structure 10 by means of a flange 34 and a shoulder 36 on the container. The flange 34 rests on the flange 26 of the tank and the shoulder 36 may rest on the shoulder 28 of the tank 12. The container 30 may be filled with concrete or other suitable material.

The motor base 22 has a flange 38 which rests on a cover plate 40 which, in turn, rests on the flange 34 at the outer rim of the container 30' and a flange 42 on the tubular sleeve 32 of the container 30. A seal 44, which may be of any suitable type, surrounds the shaft 20 and is mounted on the flange 42.

The pump component 16 is suspended from the motor support 14 by means of a cylindrical sleeve 46 which may be formed integrally with or secured to the bottom of the container 30 by welding or other suitable means. A pump supporting ring 48 is secured to the lower end of the sleeve 46 as by welding. A radial bearing assembly 50 is provided for the pump shaft 20. The bearing assembly 50 may be of any suitable type and it is attached to the ring 48 by bolts 52. A seal 54- is provided for the shaft 20 where it extends from the bearing assembly 50.

The pump 16 comprises an impeller 56, a ditfuser 58 and a casing 60. The impeller 56 shown in FIG. 1 is of a single suction, radial flow, Francis blade type. The diffuser 58 contains a plurality of vanes 62 which provide eflicient conversion of velocity energy to pressure energy.

The pump casing 60 comprises two spaced open bottom concentric bowls 64 and 66 having a discharge flow passage 68 between the concentric bowls. The inner bowl 66 has a generally cylindrical suction approach 70 therein with a wall 72 formed integrally with the bowl 66. The casing discharge passage 68 has vanes 74 therein which remove the fluid radial velocity received from the diffuser 58 and direct the flow into a discharge cone 76 described hereinafter.

The casing 60 and the diffuser 58 are clamped to the supporting ring 58 by bolts 78. The impeller 56 is attached to the shaft 20 by an impeller nut 80 and a bolt 82. As previously explained, the ring supports the radial bearing assembly 50 for the shaft 20. If the hearing assembly 50 is of a hydrostatic type it may be connected to the pump 16 by means of pipes 84 to supply liquid under pressure to the bearing assembly 50. A seal 86 is provided between the impeller 56 and the ring 48.

The suction and discharge header assembly 18 controls the flow transition between the pumping element and the piping of the circulatory system in which the pump is connected. The assembly 18 comprises a header 88, a generally cylindrical suction adapter 90 having a vertically disposed wall 92, and the discharge cone 76 which surrounds and is spaced from the adapter 90. The assembly 18 is preferably a welded structure and can be formed from steel plate.

The header 88 has an inlet opening 94 with a vertically extending wall 96 substantially in alignment with the vertical wall 92 of the suction adapter 90. The header 88 also has a discharge opening 98 with an angularly extending wall 100 substantially in alignment with the angular or flared wall 102 of the discharge cone 76. As previously explained, the openings 94 and 98 may be connected to the circulatory system piping.

In order that the entire pump component may be removed from the tank as a unit, and to permit axial movement between the pump and the tank caused by temperature transients, slip joints 104 and 106 are provided to connect the pump casing 60 with the suction and header assembly 18. These joints must seal against pump differential pressure. The joint 104 is formed between a machined portion 108 of the lower end of the wall of the outer casing bowl 64 and a machined portion 110 of the wall of the discharge cone 76. The joint 106 is formed between a machined portion 112 of the wall 72 of the inner bowl 66 and a machined portion 114 of the wall 92 of the suction adapter 90. The joints 104 and 106 are of a relatively small diameter and the concentric arrangement allows machining the joints to a relatively close tolerance. The result is less fluid leakage, and thus, higher pumping efficiency.

As previously stated, the slip joints are free to move axially to permit axial movement between the pump and the tank. The joints permit the entire pump assembly, the pump shaft and the motor support to be removed from the tank as a unit for maintenance. The concentric joint favors a lower net positive suction head (NPSH) be cause the structure permits arrangement of a straight suction approach to the impeller eye.

The present pump structure is suitable for handling a liquid metal, such as sodium, at a relatively high temperature. The tank 12 contains a pool of the liquid metal which completely submerges the hydraulic elements of the pump. In order to prevent the atmosphere from combining with the sodium, an inert gas, such as argon, fills the space between the liquid metal level and the deck shielding As previously explained, the pump flow is ducted to and from the suction and discharge header 18 so that this flow is kept separate from the liquid in the sump of the tank 12. This prevents fluid disturbance in the sump and reduces intermixing gas with the liquid metal at the gas-liquid interface. Stagnating vanes 118 are mounted on 4 the sleeve 46 to prevent swirling of the sodium at the liquid interface.

Another feature of the hydraulic component is that the net internal leakage is directed from the pump element into the sump. This simplifies the control of the sump liquid level. The leakage can be transferred back to the circulatory system by connecting an overflow pipe to an overflow outlet 120 and connecting the overflow pipe into the circulatory system. A properly constructed overflow pipe would establish a minimum liquid level at the inlet to the overflow pipe.

The hydraulic component 16' shown in FIG. 2 is of a high specific speed type which provides a relatively large flow of liquid at a relatively low head as compared with the hydraulic component shown in FIG. 1. The impeller 56 and the diffuser 58' are of the axial flow type. The pump assembly is supported by bolting an extension 122 of the pump casing 60' to a flange 124 on the lower end of the sleeve 46'. The radial bearing assembly 50' is also supported by the pump casing 60'. The concentric bowls 64' and 66' and the discharge passage 68 are also of the axial flow type. The suction and discharge openings' are of a large diameter compared with the size of the impeller. Otherwise, the pump structure and the suction and discharge header 18 are similar to the structure hereinbefore described. The slip joints 104 and 106 permit the entire pump assembly to be removed from the tank 12 in the manner hereinbefore described.

The pump component 16' shown in FIG. 3 is of a two stage type which is capable of producing a greater pressure head at a lower speed as compared with the pump component shown in FIG. 1. As shown, a second impeller 126 is secured to the shaft 20' above the first impeller 56'. The diffuser 58 is disposed between the first impeller 56 and the second impeller 126. A second diffuser 128 is disposed between the impeller 126 and the discharge passage 68' of the casing 60. The pump assembly is supported by the ring 48 which is attached to the sleeve 46 as hereinbefore described. The bearing assembly 50 for the shaft 20' is supported by the ring 48 as previously described. The slip joints 104 and 106 function in the manner hereinbefore described. Thus, the pump structures shown in FIGS. 2 and 3 fit into the same overall pump-motor concept arrangement described in connection with FIG. 1. These arrangements have the unique features hereinbefore described.

From the foregoing description it is apparent that the invention provide a pump-motor combination which is particularly suitable for handling a large quantity of liquid metal at a relatively high temperature. The hydraulic component provides adequate hydraulic efliciency and net positive suction head performance. The pump arrangement maintain a stable gas to liquid metal interface. Piping connections are made directly to the tank containing the pump component. Provision is made for thermal expansion between the pump component and the tank without affecting the external piping connections. Also, the arrangement of the suction and discharge connections between the pump and the tank are such that hydraulic losses are reduced.

Since numerous changes may be made in the abovedescribed structures and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all subject matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a pump-motor combination, a supporting structure, a vertical generally cylindrical tank suspended from said structure, a motor support at the top of the tank, a centrifugal pump casing suspended from the motor support within the tank, a suction and discharge header forming the bottom of the tank, a pump shaft extending vertically through the motor support, an impeller disposed within the casing and secured to the shaft, and slip joints connecting the casing and the header to permit the casing and the impeller and the shaft to be removed from the tank as a unit.

2. The combination defined in claim 1, wherein the slip joints are annular in shape and concentrically disposed.

3. The combination defined in claim 1, wherein the header comprises a generally cylindrical suction adapter extending upwardly inside the header and a discharge cone surrounding and spaced from the upper portion of the adapter.

4. The combination defined in claim '3, wherein said adapter and said cone cooperate with said casing to form said slip joints.

5. The combination defined in claim 3, wherein the header has an inlet opening with a vertically extending wall substantially aligned with said suction adapter and a discharge opening with an angularly extending wall substantially aligned with said discharge cone.

6. The combination defined in claim 1, wherein the casing comprises two spaced concentric open bottom bowls with the space between the walls of the bowls constituting a discharge passage for the impeller.

7. The combination defined in claim 6, wherein the inner bowl has a generally cylindrical suction approach therein with a wall connected to the header through one of said slip joints.

'8. The combination defined in claim 7, wherein the outer bowl has a wall connected to the header through another of said slip joints.

9. The combination defined in claim 6, 'wherein the casing includes a diffuser disposed bet-ween the impeller and the discharge passage.

10. The combination defined in claim 9, wherein the diffuser extends generally parallel to the axis of the impeller.

11. The combination defined in claim 9, including a second impeller secured to the shaft with the difiuser for the first impeller discharging into the second impeller.

12. The combination defined in claim 11 including a second diffuser disposed between the second impeller and the discharge passage.

References Cited UNITED STATES PATENTS 705,347 7/1902 Harris 103-103 717,096 12/1902 Harris 103103 2,134,686 11/1938 De Lanccy 103103 2,384,254 9/1945 Meredew 10387 3,158,295 11/1964 McConaghy 222333 2,673,075 3/1954 BOrck 25996 3,072,069 1/1963 Wittwer 10387 3,045,895 7/1962 Bolter et al. 230 3,165,064 1/1965 Drago 10387 FOREIGN PATENTS 124,621 9/1931 Austria.

367,924 3/1932 Great Britain.

282,183 7/ 1952 Switzerland.

HENRY F. RADUAZO, Primary Examiner US. Cl. X.R. 

